Solar desalination for agriculture irrigation in countries suffering from drought.
A LOCAL AND SUSTAINABLE SOLUTION FOR IMMEDIATE IMPACT
Securing agricultural production in countries facing a water deficit is a major challenge, especially when the objective is to guarantee food self-sufficiency for isolated populations. In their search for local and adapted solutions, more and more public and private actors are turning to solar desalination units. Implementing efficient soil irrigation with the guarantee of fresh water coming from unsafe local resources, supports secured agricultural production, sources of work, and sustainable income.
The Food and Agriculture Organization of the United Nations, FAO, predicts that by 2050, water requirements for agriculture will increase by 50% to meet the increased food demands of growing populations. At the same time, water scarcity and declining water quality in many parts of the world pose a growing threat to food security and the maintenance of global population balances.
The facts are clear: freshwater reserves are dwindling in a growing number of countries that have been suffering from water stress for several years. In order to cope with the current demographic surge causing an additional pressure on water availability, it is necessary to increase access to a quality water resource. There is therefore an urgent need to react to overcome this negative trend in the long term.
Solar Desalination: A Short and Long Term Solution
Each situation must be considered both in its globality and its context. What are the short, medium, and long term solutions to secure local food production?
First, it’s important to consider that the solution to be implemented cannot be universal and centralized. Instead, it must be entirely adapted for the local context. For that, the most basic main points to integrate in the solution are a good understanding of the farmer’s water needs in terms of quantity and quality, the integration with the policies set up by local authorities, and the state of the water resource. Therefore, solar desalination is not intended to be the ONLY solution, but a new and proven component of a set of solutions to be considered in the set up and financing of initiatives in support of agricultural activity.
In the current landscape, solar desalination has become an unavoidable alternative for clean water needs when no other local resource is available. It is a perennial solution, simple and quick to deploy. Moreover, it is sustainable because it does not generate CO2 emissions and it is inexpensive because maintenance costs are low. Solar desalination may be immediately adapted to the environment of each population. These installations are able to treat sea water, brackish water, and contaminated water. The water produced offers immediate results for populations without water nor solutions, so they fully benefit from the fruit of the land.
Cape Verde Chooses Solar Desalination
Cape Verde is a concrete example. In this country, local agriculture usually represents nearly 10% of the GDP and directly feeds a third of the population. However, due to global warming, this archipelago has reached a critical water threshold in the last 4 years: less than 200mm of rainfall on average per year and even no water at all in some localities such as the island of Santiago. These extreme climatic episodes lead more and more frequently to periods of shortage of water suitable for consumption and use in agriculture. This alarming situation has pushed the Ministry of Agriculture to react and to act on the implementation of a national mobilization policy in order to find urgent solutions for water supply and rational management of the resource. Among the various tracks favored by the government, the establishment of desalination units of brackish water powered only by local sunshine is a top contender. The Mascara company, which has developed several projects, has demonstrated the relevance of its OSMSOUN® BW solutions for small and medium scale units.
In the locality of Moia Moia, an OSMOSUN® unit for desalination of brackish water was installed in mid 2020. The unit produces 50m3 of clean water per day powered only by solar energy, without batteries. The effects were immediate with a first harvest of tomatoes, carrots, pumpkins, cucumbers and watermelon that the local farmers had not experienced in several years. This production has revived an activity that supports the families benefiting from the program.
Not a single drop of rain has fallen for nearly three years on this archipelago off the coast of West Africa …
L’urgence sanitaire face à la réalité financière
While the political will is one thing, the economic aspects and the financial set-up of each solar desalination project is another.
For solar desalination, a first important financial characteristic is that each project offers economic water production on a daily basis because maintenance costs are reduced. Indeed the operating expenses (OPEX) are strongly minimized, which is explained by the absence of recurring costs related to energy consumption. These low levels of operating expenses can be assumed and supported by the agricultural activity, ensuring the sustainability of the solution.The second important economic element concerns the financing of the investment expenses in the infrastructure (CAPEX), which covers the acquisition of quality equipment and the photovoltaic electrical production capacity. This investment can be supported by different profiles of financiers, which can be national, regional, international, public or private. The choice of the financiers in the assembly of a solution is established among others according to the expectations at the level of the direct or indirect impacts of the project.
In the case where a project owner would like to benefit directly from competitively priced water, without having to make an investment, a water sale agreement can also be directly contracted between the beneficiary and the solution provider.Finally, it should be noted that each financing modality induces delays between the decision and the payment of the first drop, which must be taken into consideration.
The Prospect of a Better Future
The return of a local economic dynamism was naturally noted. Part of the harvest is sold on the market, resulting in young people from the village now being able to find employment. Today, 28 farmers are now working the land thanks to the implementation of this solution.
The unit is maintained by a local team, which guarantees them complete autonomy in the management of their plot. The initiative has also increased the irrigated area by 3ha thanks to a drip system that optimizes water management, therefore offering each family 1180 m2 of land to cultivate under good conditions.
Another OSMOSUN® installation was built in 2021 in the town of San Santiago: the same positive effects for the population were had with the production of 40 m3 of fresh water per day.
Thanks to a vast water resources management program, Cape Verde has successfully taken up the challenge of solar desalination for agricultural use.
These concrete examples of sustainable agriculture, with real and immediate benefits, reveal to farmers but also to local decision makers and project financiers, such as international donors, the technical and economic relevance of this alternative. This solution offers a guarantee of continuous irrigation for the market gardening productions and envisions food self-sufficiency of isolated populations in a sustainable way.
In the end, the expected benefit is not simply a direct access to water, but important indirect benefits in the framework of development aid policies on a territorial scale. These indirect benefits or externalities provide a positive response to the 17 Sustainable Development Goals (SDGs) defined by the United Nations: hunger, water, poverty, decent work ….
OSMOSUN is a solution for desalination of local seawater or brackish water resources using solar energy. It is a reliable solution, a key component of a sustainable and competitive management of water resources in the face of drought. It provides a year-round supply of fresh water and thus enables continuous irrigation of agricultural land.